1. Field of the Invention
The invention relates to a pressure vessel having separate load-bearing components for circumferential and axial loads.
2. Description of the Prior Art
Generally, the maximum allowable interval pressure in a pressure vessel depends on the maximum allowable stresses in the load bearing components of the vessel. These allowable stresses are significantly higher in a vessel with separate load bearing components for axial and circumferential loads than in a conventional vessel with a single load bearing component for circumferential and axial loads. Therefore, the maximum allowable internal pressure in a pressure vessel with separate load bearing components can be significantly higher than in a conventional pressure vessel. Consequently, a pressure vessel with separate load bearing components can be designed lighter than a conventional vessel.
U.S. Pat. No. 3,368,708 discloses a pressure vessel comprising a cylindrical wall for bearing circumferential loads, means for bearing axial loads, two end caps arranged at opposite ends of the vessel and rigidly connected to the means for bearing axial loads, at least one of the end caps being axially slidable relative to the cylindrical wall, and sealing means arranged between the cylindrical wall and each slidable end cap.
In the known pressure vessel the means for bearing axial loads are the rods extending between the end caps. The tie rods pass through the interior of the vessel. The elevated fluid pressure inside the vessel exerts an outwardly oriented axial force to the end caps, which force is transmitted to the tie rods via the connecting points between the end caps and the tie rods. Consequently, inwardly oriented axial reaction forces are locally exerted by the tie rods to the end caps at said connecting points. The loading situation of the end caps is therefore asymmetrical with respect to the central longitudinal axis, leading to an asymmetrical deformation of the end caps. Such an asymmetrical deformation may impair the sealing means or lead to a skew position of the end caps relative to the central longitudinal axis.